Two fundamental concepts in welding consumable development were explored in this research. The first concept dealt with the introduction of yttrium-containing oxides into the weld metal for microstructural control and hydrogen trapping. The second concept suggested the use of fluoride species to displace hydrogen from the arc. Combining yttrium and fluorides into one single flux-cored consumable to capture the benefit of hydrogen reduction from both ingredients, however, proved to be difficult. The oxygen potential controlled by yttrium clashed with the fluorine potential controlled by KF. Several iterations led to the successful reconciliation of the oxygen potential and fluorine potential and the development of a new generation of flux-cored consumables with exceptional performance. Using CO2 as shielding gas, these consumables successfully produced welds that contained only 0.6 ml H2/100 g weld metal. With a duplex martensite-acicular ferrite microstructure, a weld metal with yield strength of 99 ksi and tensile strength of 108 ksi was obtained. The weld metal exhibited excellent ductility, 21.8% elongation. Impact toughness exceeded the −60 °F requirement by 88%, reaching values of 76 ft-lb. Charpy-V-notch energy at 0 °F testing temperature measured an outstanding average of 89 ft-lbs. Consumables designed using the two fundamental concepts have demonstrated great capability of producing high strength steel welds that met stringent mechanical performance requirements.

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